protobuf3: support cross compilation

Provide a native c compiler, which, and protoc

pkgs/development/libraries/protobuf/3.1.nix

@@ -1,6 +1,8 @@
-{ callPackage, ... }:
+{ callPackage, externalProtoc, buildProtobuf, ... }:
 
 callPackage ./generic-v3.nix {
   version = "3.1.0";
   sha256 = "0qlvpsmqgh9nw0k4zrxlxf75pafi3p0ahz99v6761b903y8qyv4i";
+  externalProtoc = externalProtoc;
+  buildProtobuf = buildProtobuf;
 }

pkgs/development/libraries/protobuf/3.4.nix

@@ -1,6 +1,8 @@
-{ callPackage, lib, ... }:
+{ callPackage, lib, externalProtoc, buildProtobuf, ... }:
 
 lib.overrideDerivation (callPackage ./generic-v3.nix {
   version = "3.4.1";
   sha256 = "1lzxmbqlnmi34kymnf399azv86gmdbrf71xiad6wc24bzpkzqybb";
+  externalProtoc = externalProtoc;
+  buildProtobuf = buildProtobuf;
 }) (attrs: { NIX_CFLAGS_COMPILE = "-Wno-error"; })

pkgs/development/libraries/protobuf/3.5.nix

@@ -1,6 +1,8 @@
-{ callPackage, lib, ... }:
+{ callPackage, lib, externalProtoc, buildProtobuf, ... }:
 
 lib.overrideDerivation (callPackage ./generic-v3.nix {
   version = "3.5.1.1";
   sha256 = "1h4xydr5j2zg1888ncn8a1jvqq8fgpgckrmjg6lqzy9jpkvqvfdk";
+  externalProtoc = externalProtoc;
+  buildProtobuf = buildProtobuf;
 }) (attrs: { NIX_CFLAGS_COMPILE = "-Wno-error"; })

pkgs/development/libraries/protobuf/3.6.nix

@@ -1,6 +1,8 @@
-{ callPackage, ... }:
+{ callPackage, externalProtoc, buildProtobuf, ... }:
 
 callPackage ./generic-v3.nix {
   version = "3.6.1";
   sha256 = "1bg40miylzpy2wgbd7l7zjgmk43l12q38fq0zkn0vzy1lsj457sq";
+  externalProtoc = externalProtoc;
+  buildProtobuf = buildProtobuf;
 }

pkgs/development/libraries/protobuf/generic-v3.nix

@@ -1,6 +1,8 @@
 { stdenv
 , fetchFromGitHub
-, autoreconfHook, zlib, gmock
+, autoreconfHook, zlib, gmock, which, buildPackages
+, externalProtoc
+, buildProtobuf ? null
 , version, sha256
 , ...
 }:
@@ -28,8 +30,11 @@ stdenv.mkDerivation rec {
       --replace 'tmpnam(b)' '"'$TMPDIR'/foo"'
   '';
 
-  nativeBuildInputs = [ autoreconfHook ];
+  nativeBuildInputs = [ autoreconfHook buildPackages.which buildPackages.stdenv.cc ]
+                      ++ stdenv.lib.optional externalProtoc [ buildProtobuf ];
+
   buildInputs = [ zlib ];
+  configureFlags = stdenv.lib.optional externalProtoc [ "--with-protoc=${buildProtobuf}/bin/protoc" ];
 
   enableParallelBuilding = true;
 

pkgs/top-level/all-packages.nix

@@ -11726,10 +11726,30 @@ with pkgs;
 
   protobuf = protobuf3_6;
 
-  protobuf3_6 = callPackage ../development/libraries/protobuf/3.6.nix { };
-  protobuf3_5 = callPackage ../development/libraries/protobuf/3.5.nix { };
-  protobuf3_4 = callPackage ../development/libraries/protobuf/3.4.nix { };
-  protobuf3_1 = callPackage ../development/libraries/protobuf/3.1.nix { };
+  protobuf3_6 = callPackage ../development/libraries/protobuf/3.6.nix {
+    externalProtoc = (stdenv.hostPlatform != stdenv.buildPlatform);
+    buildProtobuf = if (stdenv.hostPlatform != stdenv.buildPlatform)
+                    then buildPackages.protobuf3_6
+                    else null;
+  };
+  protobuf3_5 = callPackage ../development/libraries/protobuf/3.5.nix {
+    externalProtoc = (stdenv.hostPlatform != stdenv.buildPlatform);
+    buildProtobuf = if (stdenv.hostPlatform != stdenv.buildPlatform)
+                    then buildPackages.protobuf3_5
+                    else null;
+  };
+  protobuf3_4 = callPackage ../development/libraries/protobuf/3.4.nix {
+    externalProtoc = (stdenv.hostPlatform != stdenv.buildPlatform);
+    buildProtobuf = if (stdenv.hostPlatform != stdenv.buildPlatform)
+                    then buildPackages.protobuf3_4
+                    else null;
+  };
+  protobuf3_1 = callPackage ../development/libraries/protobuf/3.1.nix {
+    externalProtoc = (stdenv.hostPlatform != stdenv.buildPlatform);
+    buildProtobuf = if (stdenv.hostPlatform != stdenv.buildPlatform)
+                    then buildPackages.protobuf3_1
+                    else null;
+  };
   protobuf2_5 = callPackage ../development/libraries/protobuf/2.5.nix { };
 
   protobufc = callPackage ../development/libraries/protobufc/1.3.nix { };